Krank2O is made by the same company as Jolt Cola, and there are also other X-brands, like Water Joe, and the like.

Also, having done a small study on caffeine in high school, I've learned that it'd take about 700 cups of coffee in an hour to actually kill a person, which is physically impossible (at least, I think it is). I mean, even drinking 270 triple shots of espresso would be a bitch to get in you in the space of a few hours, but could possibly be done.

Now, if you made thickass espresso with caffeinated water, you could probably kill yourself if you could down 20 per hour for a consecutive few hours. Of course, I don't know how you'd get the cup to your mouth what with the shaking you'd be doing after the first hour, but it's possible, I guess.